Superior Toughened Biodegradable Poly(L-lactic acid)-based Blends with Enhanced Melt Strength and Excellent Low-temperature Toughness via In situ Reaction Compatibilization

The toughened poly(L-lactic acid)/poly(butylene succinate-butylene terephthalate)(PLLA/PBST) blend with enhanced melt strength and excellent low temperature toughness and strength was prepared by melt compounding through in situ compatibilization reaction in presence of multifunctional epoxy compound(ADR).The PLLA/PBST blend was an immiscible system,and the compatibility of the PLLA/PBST blend was improved after adding ADR.FTIR and GPC curves confirmed the formation of the PLLA-g-PBST copolymer,which improved the interfacial bonding of the blend and therefore the PLLA/PBST/ADR blend showed excellent melt strength and mechanical properties.For the PLLA/PBST/ADR blend with 70/30 PLLA/PBST content,the complex viscosity increased significantly with increasing ADR content.Moreover,the tensile strength,elongation at break and impact strength all increased obviously with increasing the ADR content.The elongation at break of the blend reached the maximum value of 392.7%,which was 93.2 times that of neat PLLA.And the impact strength of the blend reached the maximum value of 74.7 k J/m~2,which was 21.3 times that of neat PLLA.Interestingly,the PLLA/PBST/ADR blend exhibited excellent lowtemperature toughness and strength.At –20 ℃,the elongation at break of the PLLA/PBST/ADR blend was as high as 93.2%,and the impact strength reached 18.8 k J/m~2.Meanwhile,the tensile strength of the blend at low temperature was also high(64.7 MPa),which was beneficial to the application of PLA in the low temperature field.In addition,the PLLA/PBST/ADR blend maintaind good biodegradability,which was of great significance to the wide application of PLLA.

通过给桑蚕喂食稀土离子改性的饲料制备高强高韧的蚕丝纤维

蚕丝纤维具有优异的生物相容性和良好的力学性能,但以简单且大规模的方式生产强韧的蚕丝纤维仍是一项重大挑战.本文报道了一种通过给桑蚕喂食稀土离子改性桑叶饲料以制备强韧蚕丝纤维的方法.所得蚕丝纤维具有显著提高的拉伸强度和韧性,其平均值分别为0.85±0.07 GPa和156±13 MJ m^(-3),且最大值达到0.97±0.04 GPa和188±19 MJ m^(-3),这些性能接近蜘蛛牵引丝(自然界最强的丝纤维之一)的拉伸强度和韧性.研究结果表明,稀土离子(La^(3+)或En^(3+))成功掺入蚕丝纤维并与其形成相互作用.稀土离子减小了蚕丝纤维的直径,降低了其内部结晶组分的含量并提升了取向度.这些相互作用与结构演变同时提升了蚕丝纤维的强度和韧性.该研究提出了一种简单、可扩展且有效的生产超强韧丝纤维的策略,制备的蚕丝纤维有望应用于个人防护和航空航天等需要轻质结构材料的领域.